(a) Field of the Invention
The present invention relates to a touch sensitive display device, and a driving apparatus and method thereof, and more particularly to a display device including hardwired logic units for detecting a touch using the hardwired logic units in a power saving mode, and converts the operation mode to a normal mode when the touch is detected to reduce power consumption.
(b) Description of Related Art
A liquid crystal display (“LCD”) among display devices includes a pair of panels provided with pixel electrodes and a common electrode, respectively. A liquid crystal layer with dielectric anisotropy is interposed between the panels. The pixel electrodes are arranged in a matrix and connected to respective switching elements such as thin film transistors (“TFTs”) such that they receive image data voltages row by row. The common electrode covers the entire surface of one of the two panels, and is supplied with a common voltage. A pixel electrode and corresponding portions of the common electrode as well as corresponding portions of the liquid crystal layer form a liquid crystal capacitor that, along with a respective switching element connected thereto, is a basic element of a pixel.
An LCD generates electric fields by applying voltages to pixel electrodes and a common electrode and varies the strength of the electric fields to adjust the transmittance of light passing through a liquid crystal layer, thereby displaying images.
A touch screen panel is an apparatus on which a finger or a stylus is touched to write characters, to draw pictures, or to instruct a device such as a computer to execute instructions by using icons displayed on the touch screen panel. The touch screen panel has its own mechanism to determine whether and where a touch exists, and the touch screen panel is usually attached on a display device such as an LCD. However, an LCD provided with a touch screen panel has many disadvantages. The disadvantages include a high manufacturing cost due to the cost of the touch screen panel, low productivity due to a step for attaching the touch screen panel to the LCD, a reduction of the luminance of the LCD and an increase in the thickness of the LCD, for example.
Sensors that are incorporated into pixels in an LCD instead of using a separate touch screen panel have been developed. A sensor senses a variation of light incident on a panel caused by a user's finger, for example, to inform the LCD whether the user's finger touches the screen and where the touch occurs.
However, a large amount of power is consumed to read sensor data signals and obtain touch information from the sensor data signals. Further, power consumption of a middle-sized or small-sized LCD used in portable devices such as a cell phone, a personal digital assistant PDA, etc., needs to be minimized for carrying portable devices for extended periods without requiring recharging of the portable devices.